friend function prob.

hi,

ive made the following operator a friend because i need to access the private vector<int> set...but for some reason it gives me the following compile error
IntSet.h: In function `const IntSet operator+(const IntSet&, const IntSet&)':
IntSet.h:29: error: `std::vector<int, std::allocator<int> > IntSet::set' is
private
IntSet.cc:80: error: within this context

please note this is line 80:

Code:

 for (constSetIterator it = b.set.begin(); it!=b.set.end(); ++it) {

..y?

Code:

/* returns a union of the sets a and b */
const IntSet operator+(const IntSet &a, const IntSet &b){

       IntSet newSet = a;

       for (constSetIterator it = b.set.begin(); it!=b.set.end(); ++it) {
           if (!newSet.contains(*it))
              newSet.add(*it);
       }

       return newSet;
}

its protoype in the .h file is

Code:

friend IntSet operator+(const IntSet a, const IntSet b);

The prototype in your .h file is differente, it receives two objects, not two references. Is the prototype inside the IntSet class?

yea...i think that was the problem ...i put the non-member function in side the class making it a member function...

i have another similar problem...the compiler give the error
IntSet.cc: In function `const IntSet operator+(const IntSet&, const IntSet&)':
IntSet.cc:76: error: new declaration `const IntSet operator+(const IntSet&,
const IntSet&)'
IntSet.h:47: error: ambiguates old declaration `IntSet operator+(const IntSet&,

const IntSet&)'

this is the operator

Code:

const IntSet operator+(const IntSet &a, const IntSet &b){

       IntSet newSet = a;

       for (constSetIterator it = b.set.begin(); it!=b.set.end(); ++it) {
           if (!newSet.contains(*it))
              newSet.add(*it);
       }

       return newSet;
}

and this is its prototype

Code:

friend IntSet operator+(const IntSet &a, const IntSet &b);

btw..do u need to put the const in front of the method in the prototype..i thought you dont have to.

You don't put const "in front of the method". const is part of the return type. The friend declaration is for a function that returns an "IntSet". The definition is for a function that returns a "const IntSet". This invalidates nonsensical code such as:

Code:

(a + b) = c;